Duplicate of A027856.

Terms

a(0) =4a(1) =6a(2) =12a(3) =18a(4) =72a(5) =108a(6) =192a(7) =432a(8) =1152a(9) =2592a(10) =139968a(11) =472392a(12) =786432a(13) =995328a(14) =57395628a(15) =63700992a(16) =169869312a(17) =4076863488a(18) =10871635968